Air lift pump

ABSTRACT

AN AIR LIFT PUMP FOR USE AS A SEWAGE LIFT PUMP IS PROVIDED WITH AN AIR INJECTION SECTION IN WHICH JET NOZZLES ARE DISPOSED PERIPHERALLY AND HELICALLY AROUND THE PUMP SECTION AND ARRANGED AT ANGLES TO THE PLANES RADIAL AND TANGENTIAL TO THE LONGITUDINAL AXIS OF THE PUMP WHICH VARY WHEN PROGRESSING PERIPHERALLY AROUND THE PUMP SECTION.

June 27, 1972 J. N. WHITE ETAL 3,672,790

AIR LIFTPUMP Filed April 15, 1971 3 Sheets-Sheet 1 Fl G. I

kw l9 2 FIG.3 n

6 fl? Q I A 3 WM 32 I 35 22 l4 INVENTOR. JESSIE N. WHITE BY BERNARD ROSEBY m (L 1 M- June 21, 1912 Filed April 15. 1971 J. N. WHITE ETAL AIR LIFT PUMP 3 Sheets-Sheet 2 I I m...

INVENTOR. JESSIE N. WHITE BERNARD ROSEBY QM (L P June 27, 1972 J N, w ETAL 3,672,790

AIR LIFT PUMP 3 t e e w t n m a F 3 O M O M m U.\ W\ O 7 OP 7 7 6 5 I\ 6 5 m 1 H W M W O V. W 8% W V .W S E /H -P \k" R k, r A M :W V 4M m V A [I m V l //4 O m 2/ l 0 MM Q m B 6 4 2 0 m T m we IE 8 LW 5 INVENTOR. JESSIE N. WHITE BERNARD ROSEBY United States Patent 3,672,790 AIR LIFT PUMP Jessie N. White, Kensington, and Bernard Rosehy, Burlingame, Calif., assignors to Berkeley Steel Construction Company, Inc.

Filed Apr. 15 1971, Ser. No. 134,218 Int. Cl. F04f 1/18, 5/00 US. Cl. 4l7108 6 Claims ABSTRACT OF THE DISCLOSURE An air lift pump for use as a sewage lift pump is provided with an air injection section in which jet nozzles are disposed peripherally and helically around the pump section and arranged at angles to the planes radial and tangential to the longitudinal axis of the pump which vary when progressing peripherally around the pump section.

BACKGROUND OF THE INVENTION This invention relates generally to pumps and in particular to air lift pumps.

Air lift pumps are useful as sewage or biological waste lift pumps in that they have no moving parts in the pump itself to wear out or become damaged due to solid particles in the sewage material. They are additionally beneficial in that oxygen is entrained in the waste liquid which is utilized by the bacteria to assist in treating the biological waste prior to reaching the treatment plant.

Air lift pumps in the past operated by virtue of the vertical updraft of the air bubbles in a column of liquid which caused the liquid to be swept up with the bubbles. These pumps required the air injection device to be submerged relatively deeply compared to the lift or head requirements in order for the air bubbles to gain enough up ward momentum to lift the liquid, and to receive assistance from the static head provided by the said submergence.

Even when deeply submerged, the prior art pumps attempted to improve the efiiciency by employing various methods of injecting greater amounts of air into the liquid. Such methods included the placing of the injection orifices at a fixed angle to the direction of fluid flow and helically about the air injection section.

SUMMARY OF THE INVENTION The air lift pump of the present invention reduces the need for submerging the air injection section below the surface of the water and achieves a low submergence to lift ratio and high cfficiency through the use of air injection nozzles which are disposed peripherally around the air injection section at various angles which change from the one nozzle or group of nozzles to the next, according to a schedule, when progressing peripherally around the sec tion.

It is, therefore, an object of the present invention to provide an air lift pump of high efficiency.

It is another object of the present invention to provide an air lift pump in which a minimum of submergence of the air injection section is required.

It is a further object of the present invention to provide an air lift pump having a low submergcnce to lift ratio.

It is still another object of the present invention to provide an air lift pump for biological waste material to beneficially modify the biological oxygen demand.

Other and more particular objects of this invention will be manifest upon study of the following detailed description when taken together with the accompanying drawlugs.

Patented June 27, 1972 BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an elevational sectional view of the air injection section of the present invention:

FIG. 2 is an elevational partial sectional view of a single air injection nozzle of the air injection section;

FIG. 3 is an elevational partial sectional view of a removable air injection nozzle for use in the air injection section;

FIG. 4 is an elevational sectional view of a complete pumping system using the air lift pump of the present invention; and

FIG. 5 is a graph showing the lift as a function of air pressure for various nozzle arrangements including that of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to FIG. 1, there is illustrated an elevational sectional view of the air lift pump of the present invention comprising an air injection section 10, a pump riser section 11 and a transition section 12 for connecting air injection section 10 to pump riser section 11.

Air injection section 10 comprises cylindrical nozzle assembly 14 having an inlet end 15 and an outlet end 16 and including a plurality of air injection nozzles 17 individually identified as nozzles 17A through 17L, inclusive. Each nozzle 17 is arranged to point inwardly and upwardly in the direction of fluid flow. The longitudinal axis 19 of each jet nozzle is aligned to define an angle A and an angle B with the longitudinal axis 20 of air injection section 10 (the inside surface 21 of nozzle assembly 14 is parallel to the axis 20). That is, as seen from FIG. 1, angle A defines the inward" tilt of axis 19 toward axis 20. Angle B defines the forward" tilt of axis 19 with respect to axis 20.

Taking, for example, nozzle 17G, the angles are defined as follows:

Angle A is measured by establishing an imaginary first plane surface which contains and is coincident with longitudinal axis 20 and radial thereto, which plane is also coincident with the point of intersection of nozzle axis 19 with the extended inside surface 21 of nozzle assembly 14. For nozzle 17G, this plane would be parallel to the surface of drawing of FIG. 1.

A second imaginary plane surface is established normal or perpendicular to the first plane surface but also containing and coincident with nozzle axis 19. The angle that the line of intersection of the two planes makes with axis 20 defines angle A. Angle A shown for nozzle 176 is such an angle.

Although in FIG. 1, angle A is also measured from surface 21, through well known principles of plane geometry, the angles are the same.

Angle B is measured (for nozzle 176) by establishing an imaginary third plane surface containing and coincident with axis 20, which plane is also perpendicular to the first imaginary plane described above, and, for nozzle 17G, is also perpendicular to the surface of the drawing of FIG. 1. A fourth imaginary plane is established nor- .mal or perpendicular to the third imaginary plane but also containing and coincident with nozzle axis 19. The angle that the line of intersection of planes three and four makes with axis 20 defines angle B. Angle B shown for nozzle 17] is such an angle.

Air injection section 10 further comprises an air supply plenum 22 at the inlet end 23 of nozzles 17A-17L which is connected to a compressed air supply and control means 25 (FIG. 4) by conduit 26.

A flange 28 is provided at the outlet end 16 of section 10 which is adapted to mate with a like flange 29 connected to transition section 12 between which is a gasket 30 so that section 10 can be conveniently removed and replaced.

FIG. 2 is an enlarged view of a typical air injection nozzle 17 and comprises an inlet section 32, a venturi section 33 and an expiration section 34.

It has been found that good results are achieved when the conical angle of expiration section 34 is approximately degrees with venturi section 33 having an inside diameter of about .4 inch and a length of about /z inch.

In a similar arrangement, FIG. 3 illustrates a replaceable nozzle 35 also having an inlet section 32a, a venturi section 33a and an expiration section 34a corresponding, respectively, to inlet section 33, venturi section 34 and expiration section 35 of FIG. 2.. Replaceable nozzle 35 is provided with threads 36 along its upper end so that it can be properly aligned and attached to nozzle assembly 14. Ribs 37 connect the upper part of nozzle 35 with its lower part and permit air to flow from plenum 22 into nozzle 35.

FIG. 4 illustrates a complete pumping system using the air lift pump of the present invention. The pump is installed in a typical catch basin or manhole 38 with air injection section submerged to a point just above the bottom. A check valve 39 and a gate valve 40 are provided at the upper end of pump riser section 11 to prevent backfiow of pumped fluid during inoperation of the pump.

Compressed air is supplied to section 10 by air supply and control means 25 which comprises a compresser 42 powered by electric motor 43 which are mounted on top of compressed air tank 44.

Compressed air tank 44 supplies air to air injection section 10 through air supply regulator 45 which is controlled by pump control 46. Pump control 46 is an on and off control device which measures the liquid level in manhole 38 through air pressure measured in bubbler tube 47. Since the air pressure in tube 47 is proportional to the depth the end of tube 47 is below the surface of the liquid in manhole 38, the liquid level at which air is turned on or "off to section 10 can be established by appropriate pressure sensitive relays in pump control 46.

Power to energize motor 43 and pump control 46 is provided from power line 48 through electrical distribution panel 49.

A shut-off valve 50 and pressure regulator 51 are provided in compressed air conduit 52 between compressed air tank 44 and air supply regulator 45 and pump control 46 for manual control of the air supply.

With particular reference to FIG. 1, nozzles 17A through 173 and their angles A and B have been arranged in a particular manner to act on the fluid and propel it up through pipe riser 11.

In the specific embodiment illustrated, there are 12 nozzles, individually identified as nozzles 17A through 17L, equally spaced around the periphery of cylindrical nozzle assembly 14 and helically about assembly 14 at about an 11 degree pitch, beginning at the lower end of the helix with nozzle 17A and ending at the upper end of the helix with nozzle 17L. Nozzle 17B through 17F are not shown since they are in the front half of the sectional elevation illustrated.

Table I is a tabulation of typical values for angle A and B for a pump having a 4 to 5.25 inch inside diameter:

In the embodiment illustrated, the 12 nozzles are spaced at 30 degree intervals encompassing 360 degrees. This is not intended to limit the configuration of the present invention. The nozzles may also be spaced over a total angle greater than 360 degrees, for example, 450 degrees, 540 degrees, 540 degrees, 630 degrees, etc. Of course, the pitch of the helix defined by the nozzles may also be varied depending upon nozzle spacing and size.

To operate the pump of the present invention, the invert opening of air injection section 10 is submerged in the fluid to be pumped and compressed air is supplied from equipment as previously described.

The air flow from the nozzles, being accelerated and directed into a vortex by the venturi cross section 33 and the angular orientation of the nozzles, respectively, causes a pressure drop to be induced in the air injection section 10 below the nozzle openings further causing fluid to enter the air injection section 10 and submerge the nozzle openings, thus initiating the primary pumping action.

It can be seen that air from nozzle 17A will force the liquid at the outlet of that nozzle both upwardly, inwardly and tangentially relative to axis 20. Since angle B is large (for nozzle 17A, the angle from Table I is 26 degrees), tangential forces will be exerted on the fluid causing it to move sideways. As it moves sideways, it comes within the range of nozzle 1713 which gives it a further boost of energy sideways to successively receive energy from nozzles 17C through 17L. Also, as the liquid receives this energy the vector forces on the fluid are changing by virtue of the changes in angles A and B.

With angle A, the force changes from forcing the fluid generally upward with nozzles 17A to generally forcing the fluid generally inwardly with nozzle 17L.

With angle B, the force changes from a greater tangential force with noule 17A to a lesser tangential force with nozzle 17L.

It will also be noted that the tangential angle B is in the direction of the rising helix of noules 17A through 17L in order to follow the fluid as it rises.

With reference to FIG. 5, there is illustrated a graph of lift, in feet, along ordinate 58 and air pressure, in pounds per square inch gauge (p.s.i.g.), along abscissa 59. The lift is a measure of the maximum height that water is raised above the surface of the water being pumped.

Curve 54 shows the lift achieved with an air injection section 10 in which the nozzles are cylindrical holes arranged with their axes pointing radially inwardly on a horizontal plane.

Curve 55 shows the lift achieved with an air injection section in which the nozzles are cylindrical holes arranged with their axes pointing inwardly and upwardly with all nozzles tilted toward axis 20 at the same angle and arranged in a helix about nozzle assembly 14.

Both configurations for curves 54 and 55 required the air injection section 10 to be submerged at least 18 inches below the surface of the water to be pumped before they would operate.

Curve 56 shows the lift achieved with an air injection section in which the nozzles use a venturi orifice as described previously in which the axis of the orifice for each nozzle points inwardly and upwardly with all nozzles tilted toward axis 20 at the same angle and arranged in a helix about nozzle assembly 14.

The configuration of curve 56 required the air injection section 10 to be submerged at least 9 inches below the surface of the water to be pumped in order to operate.

Curve 57 shows the lift achieved with an air injection section in which the nozzle configuration is that of the present invention, i.e., the angle the nozzle makes with a radial plane to the pump axis increases from the bottom to the top of the helix While the angle the nozzle makes with a tangential plane decreases from the bottom to the top of the helix.

It has also been found that the configuration for curve 57 does not require air injection section 10 to be submerged below the surface of the water in order to operate.

It can also be seen that air injection section could also be placed in the middle of a pipe section to act as a booster pump or several placed in series to provide a greater lifting force to the fluid being pumped.

We claim:

1. An air lift pump comprising means defining a generally cylindrical injection section open at both ends, a plurality of inwardly pointing nozzles disposed peripherally around said injection section, the longitudinal axis of each of said nozzles defining an angle A and an angle B with the longitudinal axis of said injection section said angle A defined by the angle that the line of intersection of a first plane, which is coincident with said injection section axis and also coincident with the point of intersection of said nozzle axis and the extended inside surface of said injection section, and a second plane which is perpendicular to said first plane and coincident with said nozzle axis, makes with said injection section axis, and said angle B defined by the angle that the line of intersection of a third plane, which is coincident with said injection section axis and perpendicular to said first plane, and a fourth plane which is perpendicular to said third plane and coincident with said injection section axis, said angles A and B varying in size when progressing peripherally around said pump section, and means for providing fluid to said nozzles.

2. The air lift pump as claimed in claim 1 wherein said nozzles are disposed helieally about the periphery of said injection section.

3. The air lift pump as claimed in claim 1 wherein said angle B decreases and said angle A increases when progressing peripherally around said injection section.

4. The air lift pump as claimed in claim 1 wherein said angle A ranges from 10 to 20 degrees and said angle B ranges from 4 to 26 degrees.

5. The air lift pump as claimed in claim 1 wherein said means for providing fluid to said nozzles comprises a plenum disposed peripherally around said injection section at the inlet end of said nozzles, and means for providing compressed air to said plenum.

6. The air lift pump as claimed in claim 1 wherein said nozzles comprise an inlet section, a venturi section and an expiration section, said expiration section communicating with the interior of said injection section and said inlet section in communication with said means for providing fiuid to said nozzles.

References Cited UNITED STATES PATENTS 284,962 9/1883 Huston 417-197 334,597 1/1886 Marsh 4l7197 1,039,958 10/1912 Kimbell 417108 1,314,539 9/1919 Rust 417-108 3,340,819 9/1967 Allen 417-108 CARLTON R. CROYLE, Primary Examiner R. E. GLUCK, Assistant Examiner US. Cl. X.R. 417-197 

